# compressible flow solver in OF1.6

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 April 28, 2010, 09:33 compressible flow solver in OF1.6 #1 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 15 Hi all, Why PISO & SIMPLE algorithms are used in OF for compressible flow problems. These algorithms are for pressure linked equation i.e. incompressible flows and for low Mach no flows. Even density based solver "rhoSonicFoam" uses PISO algorithm why? In compressible flows computation, we solve momentum equation to get velocity, energy equation to get temperature, density from continuity equation and pressure from perfect gas equation. correct me if i am wrong. If this is the case, then why PISO & SIMPLE come into picture. Thanks mecbe

 April 29, 2010, 11:04 #2 Member   Ngoc-Minh Truong Join Date: Feb 2010 Location: Toulouse, France Posts: 42 Rep Power: 15 You'll find some answers here: http://www.cfd-online.com/Forums/ope...mple-piso.html Enjoy

 April 29, 2010, 12:52 #3 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 15 Hi, I read the thread and it was mentioned that steady state problem has to be solved by Pseudo Transient for stability. Can you give some details on it, because i am in the process of converting the "rhoSonicFoam" inviscid density based transient compressible flow solver(this doesn't uses PISO algorithm). thanks mecbe

 April 30, 2010, 01:07 #4 Senior Member   Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,912 Rep Power: 35 Please, define the problem you want to solve, or we cannot give any specific answer. What is the Mach number, for example? In addition, what do you mean with "converting" rhoSonicFoam? It is already a transient solver, and it doesn't use the PISO algorithm because it is density based. Best, __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

 April 30, 2010, 01:17 #5 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 15 Hi Alberto, I want to solve transonic & supersonic inviscid steady flow over missile. Mach No -0.9,1.2,1.8 & 2.5. I saw the "rhoSonicFoam" code, it doesnt uses PISO algorithm, but in tutorial case file, it was there. sorry for that. I want to convert it to steady state solver, bcz transient solver takes lot of time to converge. One more question, can you explain about the slip boundary condition (other than given in the user guide). Also, i want to implement some more inviscid flux discretization schemes like AUSM, HLLC.. Can you give some advice on how to carry on. Thanks mecbe

April 30, 2010, 01:40
#6
Senior Member

Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 35
Quote:
 Originally Posted by mecbe2002 Hi Alberto, I want to solve transonic & supersonic inviscid steady flow over missile. Mach No -0.9,1.2,1.8 & 2.5. I saw the "rhoSonicFoam" code, it doesnt uses PISO algorithm, but in tutorial case file, it was there. sorry for that. I want to convert it to steady state solver, bcz transient solver takes lot of time to converge.
You might want to take a look also to rhoCentralFoam and rhopSonicFoam.

Quote:
 One more question, can you explain about the slip boundary condition (other than given in the user guide).
What is not clear?

Best,
__________________
Alberto Passalacqua

GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541)
OpenQBMM - An open-source implementation of quadrature-based moment methods.

To obtain more accurate answers, please specify the version of OpenFOAM you are using.

 April 30, 2010, 02:37 #7 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 15 I will look into those two schemes. What about implementing new inviscid flux computation schemes like AUSM, HLLC. thanks mecbe

April 30, 2010, 12:06
#8
Senior Member

Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 35
Quote:
 Originally Posted by mecbe2002 I will look into those two schemes. What about implementing new inviscid flux computation schemes like AUSM, HLLC. thanks mecbe
There's quite some work to do to be able to implement those. You might want to take a look at aeroFoam:

http://www.cfd-online.com/Forums/ope...-aerofoam.html

Best,
__________________
Alberto Passalacqua

GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541)
OpenQBMM - An open-source implementation of quadrature-based moment methods.

To obtain more accurate answers, please specify the version of OpenFOAM you are using.

 April 30, 2010, 12:50 #9 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 15 Hi Alberto, Thanks for the thread. I downloaded the solver. This will help a lot for my work. thanks mecbe

 December 25, 2010, 09:17 #10 New Member     senthilkumar.R Join Date: Sep 2010 Location: Ranchi, India Posts: 20 Rep Power: 14 Hi mecbe, Please reply with AeroFOAM (its written for OF V 1.4.1) compatibility problem in OF V 1.6 + .